在工作中，遇到用node.js spawn调用curl方法向Mailchimp导入用户数据的情形。
一、child.stdout.on的机制
一开始的代码如下：
const spawn = require('child_process').spawn
const args = `curl --request POST \
--url '${BASE_URL}/3.0/lists/${LIST_ID}' \
--user 'user:${API_KEY}' \
--header 'content-type:application/json' \
--data '${postData}' \
--include`
const child = spawn('curl', [args], {
shell: true
})
child.stdout.on('data', (data) => {
console.log(data)
});
console.log(data)的结果是：
HTTP/1.1 200 OK
Server: openresty
Content-Type: application/json; charset=utf-8
Content-Length: 4530
Vary: Accept-Encoding
X-Request-Id: 19ae5ea8-1f1a-4cb8-a142-074887140753
Link: <https://us19.api.mailchimp.com/schema/3.0/Lists/Instance.json>; rel="describedBy", <https://us19.admin.mailchimp.com/lists/members/?id=16769>; rel="dashboard"
Date: Thu, 06 Sep 2018 15:25:49 GMT
Connection: keep-alive
Set-Cookie: _AVESTA_ENVIRONMENT=prod; path=/
Set-Cookie: _mcid=1.03c96f827b0fce334cb3f36bf2ec5667; expires=Fri, 06-Sep-2019 15:25:49 GMT; Max-Age=31536000; path=/; domain=.mailchimp.com
{"new_members":[],"updated_members":[],"errors":[{"email_address":"info@edicomex.com.mx_cancel","error":"Please provide a valid email address."}],"total_created":0,"total_updated":0,"error_count":1,"_links":[{"rel":"self","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Response.json"},{"rel":"parent","href":"https://us19.api.mailchimp.com/3.0/lists","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists.json"},{"rel":"update","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0","method":"PATCH","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Response.json","schema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/PATCH.json"},{"rel":"batch-sub-unsub-members","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0","method":"POST","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/BatchPOST-Response.json","schema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/BatchPOST.json"},{"rel":"delete","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0","method":"DELETE"},{"rel":"abuse-reports","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/abuse-reports","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Abuse/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/Abuse.json"},{"rel":"activity","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/activity","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Activity/Response.json"},{"rel":"clients","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/clients","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Clients/Response.json"},{"rel":"growth-history","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/growth-history","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Growth/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/Growth.json"},{"rel":"interest-categories","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/interest-categories","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/InterestCategories/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/InterestCategories.json"},{"rel":"members","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/members","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Members/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/Members.json"},{"rel":"merge-fields","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/merge-fields","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/MergeFields/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/MergeFields.json"},{"rel":"segments","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/segments","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Segments/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/Segments.json"},{"rel":"webhooks","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/webhooks","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Webhooks/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/Webhooks.json"},{"rel":"signup-forms","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/signup-forms","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/SignupForms/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/SignupForms.json"},{"rel":"locations","href":"https://us19.api.mailchimp.com/3.0/lists/5b524f3ac0/locations","method":"GET","targetSchema":"https://us19.api.mailchimp.com/schema/3.0/Definitions/Lists/Locations/CollectionResponse.json","schema":"https://us19.api.mailchimp.com/schema/3.0/CollectionLinks/Lists/Locations.json"}]}
我其实想直接拿到{"new_members":以后的东西，所以我做了如下操作(其实是同事帮忙哈哈)：
const spawn = require('child_process').spawn
const args = `curl --request POST \
--url '${BASE_URL}/3.0/lists/${LIST_ID}' \
--user 'user:${API_KEY}' \
--header 'content-type:application/json' \
--data '${postData}' \
--include`
const child = spawn('curl', [args], {
shell: true
})
child.stdout.on('data', (data) => {
const rData = data.toString('utf8').split('\n')
const da = (rData[rData.length - 1])
let chunksObject = JSON.parse(da)
console.log(chunksObject)
});
child.on('close', (code) => {
console.log(`child process close code：${code}`);
});
可以看到，我先通过const rData = data.toString('utf8').split('\n')把stdout出来的buffer转成utf-8格式的字符串，再通过\n即换行符切分字符串，最后取最后一位const da = (rData[rData.length - 1])为我想要的{"new_members": 部分。最后通过JSON.parse(da)得到我想要的JSON格式数据。
一开始数据量小的时候还好，等数据量一大，就发现JSON.parse(da)会报错，说da不是一个JSON格式的字符串。
查询资料发现：
node.js官网里说:
原来，stdout吐出来的东西是一个buffer，所以它应该是一段一段吐出来的。为了验证猜想，我在child.stdout.on里加了一段console.log('------------')
child.stdout.on('data', (data) => {
console.log('------------')
const rData = data.toString('utf8').split('\n')
const da = (rData[rData.length - 1])
let chunksObject = JSON.parse(da)
console.log(chunksObject)
});
运行脚本，一次curl请求打印了4到5次------------，验证了其是buffer。
于是我想，不能在每次stdout处解析data了，因为它此时data是不完整的，应该在child.on('close')时，即整个buffer输出完毕后再解析。
所以我定义了一个全局变量allChunksString，然后将每次stdout出来的chunk拼接起来，最后在child.on('close')的时候去解析allChunksString：
const spawn = require('child_process').spawn
const args = `curl --request POST \
--url '${BASE_URL}/3.0/lists/${LIST_ID}' \
--user 'user:${API_KEY}' \
--header 'content-type:application/json' \
--data '${postData}' \
--include`
const child = spawn('curl', [args], {
shell: true
})
let allChunksString = '' // a global variable to concat all the stdout chunks
child.stdout.on('data', (data) => {
const rData = data.toString('utf8').split('\n')
const da = (rData[rData.length - 1])
allChunksString += da
});
child.on('close', (code) => {
let chunksObject = JSON.parse(allChunksString)
console.log(chunksObject)
console.log(`child process close code：${code}`);
});
果然，现在JSON.parse就没有再报错了。
总结：child.stdout.on里的结果是一个buffer，一段一段的结果，所以不能出来一次解析一次，应该将其组装起来，最后到整个buffer输出完毕后在close事件里一起解析。
二、向Mailchimp API里发送的数据格式有问题
完成上述工作后，发现还是有400多条用户数据无法导入导Mailchimp中。报错shema expect object but got NULL。最后和同事千辛万苦找出来坑爹的结果，是因为有用户填入的某项merge_field字段带有'(英文单引号)。这个有开始符却没有结束符的'问题导致整个curl的data部分数据紊乱，因为curl认为你这里的data不是正确的JSON格式，所以直接给你报错结束进程。一条数据的错误，导致一起的200条用户都没法导入(我是每200条用户导入一次。)
所以，用正则将'替换成了空格,
postData = postData.replace(/\'/g, " ") // in case some user's field has ' which will mess the shell script
然后发现可以全部导入了。
当然这不是最优解，因为将用户的'改成了空格。
坑！
